Picture frame



FIG. 1 is a front elevational view of a picture frame embodying my new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a right side elevation thereof, the left side elevation being a mirror image;

FIG. 4 is a top plan view thereof; and

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a picture frame, as shown and described. 